AimTo analyze the effects of I/D polymorphism at intron 16 in the angiotensin-converting enzyme (ACE) gene, abdominal obesity and the interaction between the two factors on essential hypertension.MethodsTwo hundred and thirty-five patients without taking anti-hypertension medication and two hundred and forty normotension controls were randomly recruited from four communities in Qingdao.I/D polymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).Additive model was used to analyze the interaction between I/D polymorphism and abnormality of waist-to-hip ratio (WHR).ResultsD allele frequency and abnormality of WHR in patients were significantly higher than those in controls (48.09% and 69.79% vs 37.08% and 47.92%, p<0.05).I/D polymorphism of ACE gene and abnormality of WHR showed a positive interaction.After adjusting the age, gender, drinking, smoking, passive smoking, body mass index and blood fats by logistic regression, synergy index was 1.616, attributable interaction was 0.558, attributable interaction percentage was 22.65 %, pure attributable interaction percentage was 38.11%.ConclusionI/D polymorphism in ACE gene and abnormality of WHR might serve as a major susceptible factor of essential hypertension.I/D polymorphism of ACE gene and abnormality of WHR show a positive interaction.Proper abdominal obesity control can reduce the risk of getting essential hypertension in general population.